Packaging substrate having embedded through-via interposer and method of fabricating the same

ABSTRACT

A packaging substrate having an embedded through-via interposer is provided, including an encapsulant layer, a through-via interposer embedded in the encapsulant layer and having a plurality of conductive through-vias therein, a redistribution layer embedded in the encapsulant layer and formed on the through-via interposer so as to electrically connect with first end surfaces of the conductive through-vias, and a built-up structure formed on the encapsulant layer and the through-via interposer for electrically connecting second end surfaces of the conductive through-vias. As such, the first end surfaces of the conductive through-vias are electrically connected to the redistribution layer to thereby be electrically connected to electrode pads of a semiconductor chip having smaller pitches, while the second end surfaces of the conductive through-vias electrically connect with conductive vias of the built-up structure having larger pitches, thereby allowing the packaging substrate to be coupled with the semiconductor chip.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to packaging substrates and methods offabricating the same, and, more particularly, to a packaging substratehaving an embedded through-via interposer for carrying a semiconductorchip and a method of fabricating the same.

2. Description of Related Art

FIG. 1 is a schematic cross-sectional view of a conventional flip-chippackage structure. In fabrication, a bismaleimide-triazine (BT)packaging substrate 10 that has a core board 102, a first surface 10 aand a second surface 10 b is provided, and a plurality of flip-chipbonding pads 100 are formed on the first surface 10 a of the packagingsubstrate 10; the flip-chip bonding pads 100 are electrically connectedto conductive lands 120 of a semiconductor chip 12 through a pluralityof solder bumps 11; then, an underfill 17 is applied to fill the gapbetween the first surface 10 a of the packaging substrate 10 and thesemiconductor chip 12 for encapsulating the solder bumps 11; and thesecond surface 10 b of the packaging substrate 10 has a plurality ofsolder pads 101 so as for solder balls 13 to be mounted thereon andelectrically connect the solder pads 101 to another electronic devicesuch as a printed circuit board (not shown).

To improve the electrical performance of the semiconductor chip 12, adielectric material having an extreme low k (ELK) or an ultra low k(ULK) is usually used in a back-end of line (BEOL) of the semiconductorchip 12. However, such a low-k dielectric material is porous andbrittle. Therefore, during a thermal cycling test for reliabilitycharacterization of the flip-chip packaging structure, the solder bumps11 easily crack due to uneven thermal stresses caused by a significantdifference between the thermal expansion coefficients (C′I′E) of thepackaging substrate 10 and the semiconductor chip 12, thereby easilycausing the semiconductor chip 12 to crack and hence reducing theproduct reliability.

Further, along with the development of thin-profiled and compact-sizedelectronic products having a variety of functions, the semiconductorchip 12 has to have a high density of nano-scale circuits and thusreduced pitches between the conductive lands 120. However, the flip-chipbonding pads 100 of the packaging substrate 10 are of micro-scalepitches, which do not match the high-density nano-scale circuits of thesemiconductor chip 12.

Therefore, there is a need to provide a packaging substrate and a methodof fabricating the same so as to overcome the above-described drawbacks.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a packaging substrate havingan embedded through-via interposer, comprising: an encapsulant layerhaving opposite first and second surfaces; a through-via interposerembedded in the encapsulant layer and having opposite first and secondsides and a plurality of conductive through-vias in communication withthe first and second sides, wherein each of the conductive through-viashas a first end surface on the first side of the through-via interposerand a second end surface on the second side of the through-viainterposer, and the second side of the through-via interposer is flushwith the second end surfaces of the conductive through-vias and thesecond surface of the encapsulant layer; a redistribution layer embeddedin the encapsulant layer and formed on the first side of the through-viainterposer and the first end surfaces of the conductive through-vias soas to electrically connect with the first end surfaces of the conductivethrough-vias, wherein the outermost layer of the redistribution layerhas electrode pads; and a built-up structure formed on the secondsurface of the encapsulant layer, the second side of the through-viainterposer and the second end surfaces of the conductive through-vias,and having at least a dielectric layer, a circuit layer embedded in thedielectric layer and a plurality of conductive vias formed in thedielectric layer for electrically connecting with the circuit layer,wherein portions of the conductive vias electrically connect with thesecond end surfaces of the conductive through-vias, respectively.

The present invention provides another packaging substrate having anembedded through-via interposer, comprising: an encapsulant layer havingopposite first and second surfaces; a through-via interposer embedded inthe encapsulant layer and having opposite first and second sides and aplurality of conductive through-vias in communication with the first andsecond sides, wherein each of the conductive through-vias has a firstend surface on the first side of the through-via interposer and a secondend surface on the second side of the through-via interposer, the secondside of the through-via interposer is exposed from the second surface ofthe encapsulant layer, and the second end surfaces of the conductivethrough-vias protrude above the second side of the through-viainterposer and the second surface of the encapsulant layer to serve asconductive bumps; a redistribution layer embedded in the encapsulantlayer and formed on the first side of the through-via interposer and thefirst end surfaces of the conductive through-vias so as to electricallyconnect with the first end surfaces of the conductive through-vias,wherein the outermost layer of the redistribution layer has electrodepads; and a built-up structure formed on the second surface of theencapsulant layer, the second side of the through-via interposer and theconductive bumps, and having at least a dielectric layer, a circuitlayer formed on the dielectric layer and a plurality of conductive viasformed in the dielectric layer for electrically connecting with thecircuit layer, wherein portions of the conductive vias electricallyconnect with the conductive bumps, respectively.

The present invention further provides a method of fabricating apackaging substrate having an embedded through-via interposer,comprising: providing a through-via interposer having opposite first andsecond sides and a plurality of conductive through-vias in communicationwith the first and second sides, wherein each of the conductivethrough-vias has a first end surface on the first side of thethrough-via interposer and a second end surface on the second side ofthe through-via interposer, and the second end surfaces of theconductive through-vias are flush with the second side of thethrough-via interposer; forming a redistribution layer on the first sideof the through-via interposer and the first end surfaces of theconductive through-vias such that the redistribution layer electricallyconnects with the first end surfaces of the conductive through-vias,wherein the outermost layer of the redistribution layer has electrodepads; forming an encapsulant layer to encapsulate and embed thethrough-via interposer, wherein the encapsulant layer has opposite firstand second surfaces, and the second side of the through-via interposerand the second end surfaces of the conductive through-vias are flushwith the second surface of the encapsulant layer, and the encapsulantlayer covers the redistribution layer and the electrode pads; andforming a built-up structure on the second surface of the encapsulantlayer, the second side of the through-via interposer and the second endsurfaces of the conductive through-vias, wherein the built-up structurehas at least a dielectric layer, a circuit layer embedded in thedielectric layer and a plurality of conductive vias formed in thedielectric layer for electrically connecting with the circuit layer,wherein portions of the conductive vias electrically connect with thesecond end surfaces of the conductive through-vias, respectively.

The present invention further provides another method of fabricating apackaging substrate having an embedded through-via interposer,comprising: providing a through-via interposer having opposite first andsecond sides and a plurality of conductive through-vias in communicationwith the first and second sides, wherein each of the conductivethrough-vias has a first end surface on the first side of thethrough-via interposer and a second end surface on the second side ofthe through-via interposer, and the second end surfaces of theconductive through-vias protrude above the second side of thethrough-via interposer to serve as conductive bumps; forming aredistribution layer on the first side of the through-via interposer andthe first end surfaces of the conductive through-vias such that theredistribution layer electrically connects with the first end surfacesof the conductive through-vias, wherein the outermost layer of theredistribution layer has electrode pads; forming an encapsulant layer toencapsulate and embed the through-via interposer, wherein theencapsulant layer has opposite first and second surfaces, the secondside of the through-via interposer is exposed from the second surface ofthe encapsulant layer, the conductive bumps protrude above the secondsurface of the encapsulant layer, and the encapsulant layer covers theredistribution layer and the electrode pads; and forming a built-upstructure on the second surface of the encapsulant layer, the secondside of the through-via interposer and the conductive bumps, wherein thebuilt-up structure has at least a dielectric layer, a circuit layerformed on the dielectric layer and a plurality of conductive vias formedin the dielectric layer for electrically connecting with the circuitlayer, wherein portions of the conductive vias electrically connect withthe conductive bumps, respectively.

According to the present invention, first end surfaces of the conductivethrough-vias of the through-via interposer electrically connect with theredistribution layer to thereby electrically connect to electrode padsof a semiconductor chip having smaller pitches, and second end surfacesof the conductive through-vias electrically connect with the conductivevias of the built-up structure having larger pitches, thereby allowingthe packaging substrate to be coupled with the semiconductor chip havinghigh-density circuits. Therefore, the present invention overcomes theconventional drawback of mismatch between packaging substrates andsemiconductor chips having high-density circuits without changingoriginal supply chains and infrastructures of IC industries.

Further, if a semiconductor chip is disposed on the through-viainterposer, since the CTEs of the through-via interposer and thesemiconductor chip are close to each other, cracking of solder bumpsbetween the semiconductor chip and the through-via interposer isprevented, thereby effectively improving the product reliability.

Furthermore, the present invention embeds the through-via interposer inthe encapsulant layer so as to reduce the thickness of the overallstructure. In addition, since the built-up structure is formed on thesecond surface of the encapsulant layer, the present inventioneliminates the need of a core board as in the prior art, which alsofacilitates reduction of the thickness of the overall structure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view showing a conventionalflip-chip package structure;

FIGS. 2A to 2J are schematic cross-sectional views illustrating a methodof fabricating a packaging substrate having an embedded through-viainterposer according to a first embodiment of the present invention,wherein FIGS. 2I′ and 2I″ show different embodiments from FIG. 2I, andFIGS. 2J′, 2J″ and 2K show different embodiments from FIG. 2J;

FIGS. 3A to 3E are schematic cross-sectional views illustrating a methodof fabricating a packaging substrate having an embedded through-viainterposer according to a second embodiment of the present invention,wherein FIGS. 3D′ and 3D″ show different embodiments from FIG. 3D, andFIGS. 3E′ and 3E″ show different embodiments from FIG. 3E; and

FIGS. 4A, 4A′ and 4A″ are schematic cross-sectional views showing apackaging substrate having an embedded through-via interposer accordingto a third embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following illustrative embodiments are provided to illustrate thedisclosure of the present invention, these and other advantages andeffects can be apparent to those in the art after reading thisspecification.

It should be noted that all the drawings are not intended to limit thepresent invention. Various modification and variations can be madewithout departing from the spirit of the present invention. Further,terms, such as “one,” “on,” “top,” “bottom,” etc., are merely forillustrative purpose and should not be construed to limit the scope ofthe present invention.

FIGS. 2A to 2J are schematic cross-sectional views illustrating a methodof fabricating a packaging substrate having an embedded through-viainterposer according to a first embodiment of the present invention.

Referring to FIG. 2A, an interposer 20′ is provided. The interposer 20′has opposite first side 20 a and second side 20 b′. A plurality ofthrough-vias 200′ are formed at the first side 20 a of the interposer20′.

In an embodiment, the interposer 20′ is made of silicon.

Referring to FIG. 2B, an insulating layer 201 is formed on sidewalls andbottom portions of the through-vias 200′, and a copper material isapplied to fill the through-vias 200′ so as to form a plurality ofconductive through-vias 200. Each of the conductive through-vias 200 hasa first end surface 200 a and a second end surface 200 b correspondingto the first side 20 a and the second side 20 b′ of the interposer 20′,respectively.

In an embodiment, the conductive through-vias 200 are made of Ni, Au, W,Al or a conductive paste, and insulating layer 201 is made of SiO₂,Si₃N₄ or a polymer material. Further, the first end surfaces 200 a ofthe conductive through-vias 200 are flush with the first side 20 a ofthe interposer 20′.

In another embodiment, the interposer 20′ is made of an insulatingmaterial, such as a glass material or a ceramic material, such as Al₂O₃and AlN. As such, the conductive through-vias 200 are directly formed inthe interposer 20′ without the need of formation of the insulating layer201. Since related techniques are well known in the art, detaileddescription thereof is omitted.

Referring to FIG. 2C, a redistribution layer (RDL) 21 is formed on thefirst side 20 a of the interposer 20′ and the first end surfaces 200 aof the conductive through-vias 200 such that the redistribution layer 21electrically connects with the first end surfaces 200 a of theconductive through-vias 200. The outermost layer of the redistributionlayer 21 has a plurality of electrode pads 210.

Referring to FIG. 2D, the first side 20 a of the interposer 20′ and theredistribution layer 21 are attached to a carrier (not shown), and thesecond side 20 b of the interposer 20′ is polished, such that the secondend surfaces 200 b of the conductive through-vias 200 are exposed fromthe second side 20 b of the interposer 20′. Then, the carrier isremoved. Through the above-described fabrication processes, thethrough-via interposer 20 is obtained.

In an embodiment, the second end surfaces 200 b of the conductivethrough-vias 200 are flush with the second side 20 b of the interposer20, and the conductive through-vias 200 are in communication with thefirst side 20 a and the second side 20 b of the interposer 20. Inaddition, the insulating layer 201 is formed only on the sidewalls ofthe conductive through-vias 200.

Furthermore, the carrier is made of a material that is the same as orsimilar to the interposer 20′. For example, the carrier is made ofsilicon or an insulating material, such as a glass material or a ceramicmaterial, such as Al₂O₃ and AlN, thereby facilitating the bondingbetween the carrier and the interposer 20′. In an embodiment, thecarrier is made of a glass material.

In an embodiment, the carrier is adhered to the interposer 20′.

Referring to FIG. 2E, a plurality of interposers 20 are obtained bycutting along imaginary scribing lines K.

Referring to FIG. 2F, the through-via interposers 20 are rearranged on aglass carrier (not shown), with the second sides 20 b of the through-viainterposers 20 and the second end surfaces 200 b of the conductivethrough-vias 200 bonded with the glass carrier. Then, an encapsulantlayer 22 is formed to encapsulate the through-via interposers 20 suchthat the through-via interposers 20 are embedded in the encapsulantlayer 22. Subsequently, the glass carrier is removed.

In an embodiment, the encapsulant layer 22 has opposite first surface 22a and second surfaces 22 b. The second sides 20 b of the interposers 20and the second end surfaces 200 b of the conductive through-vias 200 areflush with the second surface 22 b of the encapsulant layer 22, and theencapsulant layer 22 covers the redistribution layer 21 and theelectrode pads 210.

Referring to FIGS. 2G to 2I, a built-up structure 23 is formed on thesecond surface 22 b of the encapsulant layer 22, the second sides 20 bof the interposers 20, and the second end surfaces 200 b of theconductive through-vias 200.

Referring to FIG. 2G, a dielectric layer 230 such as an ajinomotobuild-up film (ABF) is formed, and a plurality of circuit intaglios(including vias) 230 a are formed in the dielectric layer 230 by a lasertechnique for the second end surfaces 200 b of the conductivethrough-vias 200 to be exposed therefrom. In an embodiment, thedielectric layer 230 is formed by coating or lamination technique, andmade of polyimide (PI), prepreg (PP) or benzocyclobutene (BCB).

Referring to FIG. 2H, a circuit layer 231 and a plurality of conductivevias 232′ are formed in the circuit intaglios 230 a by an electroplatingtechnique such that the circuit layer 231 is embedded in the dielectriclayer 230 and the conductive vias 232′ electrically connect with thesecond end surfaces 200 b of the conductive through-vias 200. In anembodiment, a copper material is applied on the dielectric layer 230 andin the circuit intaglios 230 a to serve as a conductive layer (notshown), and a metal material is applied on the dielectric layer 230 andin the circuit intaglios 230 a by an electroplating technique, therebyforming the circuit layer 231 and the conductive vias 232′. Finally,portions of the metal material and the conductive layer disposed on thedielectric layer 230 are removed.

The present invention eliminates the need to use an etching technique toform the circuit layer 231, thereby avoiding side-etching of circuits byan etching solution and avoiding fabricating circuits of large size.Therefore, when the through-via interposer 20 of small size is used,high precision circuits can be fabricated to electrically connect withthe conductive through-vias 200.

Referring to FIG. 2I, a multi-layer circuit structure may be formedaccording to practical needs. In an embodiment, the built-up structure23 has at least a dielectric layer 230, a circuit layer 231 embedded inthe dielectric layer 230, and a plurality of conductive vias 232 formedin the dielectric layer 230 and electrically connected with the circuitlayer 231. Portions of the conductive vias 232′ electrically connectwith the second end surfaces 200 b of the conductive through-vias 200.

Further, an insulating protective layer 24 is formed on the built-upstructure 23, and a plurality of openings 240 are formed in theinsulating protective layer 24 such that portions of the circuit layer231 are exposed from the openings 240 to serve as conductive pads 233.

In other embodiments, the thickness of the encapsulant layer 22 may bedecreased from the first surface 22 a thereof so as to expose theelectrode pads 210 from the first surface 22 a′ 22 a″, thereby allowinga semiconductor chip (not shown) to be mounted thereon. Referring toFIG. 2I′, a plurality of openings 220 are formed on the first surface 22a′ of the encapsulant layer 22 for the electrode pads 210 to be exposedfrom the openings 220. Alternatively, as shown in FIG. 2I″, the firstsurface 22 a″ of the encapsulant layer 22 is flush with or lower thanthe electrode pads 210 so as for the electrode pads 210 to be exposedfrom the first surface 22 a″ of the encapsulant layer 22.

Referring to FIGS. 2J, 2J′ and 2J″, the structure of FIGS. 2I, 2I′ or2I″ is singulated along imaginary scribing lines L of FIG. 2I so as toobtain a plurality of packaging substrates 2, 2′ or 2″ having anembedded through-via interposer 20.

Before or after the singulation process, a plurality of solder balls 25can be mounted on the conductive pads 233 for other electronic devicessuch as printed circuit boards or semiconductor packages to be mountedthereon.

As shown in FIG. 2K, in a packaging substrate 5 according to anotherembodiment the circuit layer 231′ of the built-up structure 23 is formedon the surface of the dielectric layer 230 instead of being embedded inthe dielectric layer 230.

The present invention further provides a packaging substrate 2, 2′, 2″having an embedded through-via interposer 20. The packaging substrate 2,2′, 2″ comprises an encapsulant layer 22 having a first surface 22 a, 22a′, 22 a″ and an opposite second surface 22 b; a through-via interposer20 embedded in the encapsulant layer 22, a redistribution layer 21embedded in the encapsulant layer 22 and formed on the through-viainterposer 20, a built-up structure 23 formed on the second surface 22 bof the encapsulant layer 22, and an insulating protective layer 24formed on the built-up structure 23.

The through-via interposer 20 has opposite first surface 20 a and secondside 20 b, and a plurality of conductive through-vias 200 incommunication with the first side 20 a and the second side 20 b. Each ofthe conductive through-vias 200 has a first end surface 200 a on thefirst side 20 a of the through-via interposer 20, and a second endsurface 200 b on the second side 20 b of the through-via interposer 20,and an insulating layer 201 is formed on the sidewall of the conductivethrough-via 200. The second side 20 b of the through-via interposer 20and the second end surfaces 200 b of the conductive through-vias 200 areflush with the second surface 22 b of the encapsulant layer 22.

The redistribution layer 21 is disposed on the first side 20 a of thethrough-via interposer 20 and the first end surfaces 200 a of theconductive through-vias 200 and electrically connects with the first endsurfaces 200 a of the conductive through-vias 200. The outermost layerof the redistribution layer 21 has a plurality of electrode pads 210.

The encapsulant layer 22 covers the electrode pads 210, as shown in FIG.2J. Alternatively, referring to FIGS. 2J′ and 2J″, the electrode pads210 are exposed from the first surface 22 a′, 22 a″ of the encapsulantlayer 22.

The built-up structure 23 is further formed on the second side 20 b ofthe through-via interposer 20 and the second end surfaces 200 b of theconductive through-vias 200. The built-up structure 23 has at least adielectric layer 230, a circuit layer 231 embedded in the dielectriclayer 230, and a plurality of conductive vias 232 formed in thedielectric layer 230 and electrically connecting with the circuit layer231. Portions of the conductive vias 232′ electrically connected withthe second end surfaces 200 b of the conductive through-vias 200.

The insulating protective layer 24 has a plurality of openings 240 suchthat portions of the circuit layer 231 are exposed from the openings 240to serve as conductive pads 233.

According to the present invention, the first end surfaces 200 a of theconductive through-vias 200 electrically connect with the redistributionlayer 21 to thereby electrically connect to the electrode pads of asemiconductor chip (not shown) that have smaller pitches, and the otherend surfaces 200 b of the conductive through-vias 200 electricallyconnect with the conductive vias 232′ of the built-up structure 23 thathave larger pitches, thereby allowing the packaging substrate 2, 2′, 2″to be coupled with the semiconductor chip having high-density circuits.

Further, the through-via interposer 20 and the semiconductor chip haveCTEs of about 2.6 ppm and are close to each other, cracking of solderbumps between the semiconductor chip and the through-via interposer 20is prevented, thereby effectively improving the product reliability.

Furthermore, the present invention embeds the through-via interposer 20in the encapsulant layer 22 so as to reduce the thickness of the overallstructure. In addition, since the built-up structure 23 is formed on thesecond surface 22 b of the encapsulant layer 22, the present inventioneliminates the need of a core board as in the prior art, which alsofacilitates reduction of the thickness of the overall structure.

FIGS. 3A to 3E are schematic cross-sectional views illustrating a methodof fabricating a packaging substrate 3 having an embedded through-viainterposer 30 according to a second embodiment of the present invention.The second embodiment differs from the first embodiment in that thethrough-via interposer 30 of the second embodiment has a plurality ofconductive bumps 301.

Referring to FIG. 3A, a through-via interposer 20 as shown in FIG. 2D isprovided.

Referring to FIG. 3B, portions of the second side 20 b of thethrough-via interposer 20 are removed such that the second end surfaces300 b of the conductive through-vias 300 protrude above the second side30 b of the through-via interposer 30. The protruding portions of theconductive through-vias 300 serve as conductive bumps 301 (including theinsulating layer 201).

Referring to FIG. 3C, the structure is singulated along imaginaryscribing lines K of FIG. 3B to obtain a plurality of through-viainterposers 30.

Then, an encapsulate layer 22 having opposite first side 22 a and secondsurface 22 b is formed to encapsulate and embed the through-viainterposers 30. The second sides 30 b of the through-via interposers 30are exposed from the second surface 22 b of the encapsulant layer 22,and the conductive bumps 301 protrude from the second surface 22 b ofthe encapsulant layer 22. Further, the encapsulant layer 22 covers theredistribution layer 21 and the electrode pads 210.

Referring to FIG. 3D, a built-up structure 23 is formed on the secondsurface 22 b of the encapsulant layer 22, the second sides 30 b of thethrough-via interposers 30, and the conductive bumps 301. The built-upstructure 23 has at least a dielectric layer 230, a circuit layer 231embedded in the dielectric layer 230, and a plurality of conductive vias232 formed in the dielectric layer 230 and electrically connected withthe circuit layer 231. Portions of the conductive vias 232′ electricallyconnect with the conductive bumps 301.

Then, an insulating protective layer 24 is formed on the built-upstructure 23, and a plurality of openings 240 are formed in theinsulating protective layer 24 such that portions of the circuit layer231 are exposed from the openings 240 to serve as conductive pads 233.

In other embodiments, the thickness of the encapsulant layer 22 aredecreased from the first surface 22 a thereof so as to expose theelectrode pads 210. Referring to FIG. 3D′, a plurality of openings 220are formed on the first surface 22 a′ of the encapsulant layer 22 forthe electrode pads 220 to be exposed from the openings 220.Alternatively, referring to FIG. 3D″, the first surface 22 a″ of theencapsulant layer 22 is flush with or lower than the electrode pads 210so as to expose the electrode pads 210.

Referring to FIGS. 3E, 3E′ and 3E″, the structures 3D, 3D′ and 3D″ aresingulated along the imaginary scribing lines L of FIG. 3D so as toobtain a plurality of packaging substrates 3, 3′ and 3″ having anembedded through-via interposer 30.

Before or after the singulation process, a plurality of solder balls 25can be mounted on the conductive pads 233 for electrically connecting toother electronic devices such as printed circuit boards or packages.

According to the present embodiment, the second end surfaces 300 b ofthe conductive through-vias 300 protrude above the second sides 30 b ofthe through-via interposers 30 to serve as conductive bumps 301. Whenthe circuit intaglios 230 a are formed in the built-up structure 23 viaa laser technique, high temperature and pressure generated due theapplication of the laser technique can be absorbed by the conductivebumps 301 made of a hard material, thereby avoiding damage of thethrough-via interposers 30 made of a brittle material.

If the second end surfaces 200 b of the conductive through-vias 200 areflush with the second side 20 b of the through-via interposer 20, asshown in FIG. 3A, conductive bumps can be directly bonded to the secondend surfaces 200 b of the conductive through-vias 200 instead ofremoving portions of the through-via interposers 20 from the secondsides 20 b to form the conductive bumps 301, in order to prevent theinterposer 20 from being damaged when the circuit intaglios 230 a areformed by a laser technique. However, the conductive bumps thus formedhave a height of at least 30 μm, thereby adversely affectingminiaturization of the through-via interposers 30.

If the second end surfaces 200 b of the conductive through-vias 200 areflush with the second side 20 b of the through-via interposer 20, asshown in FIG. 3A, an electroless nickel/gold process must be performedon the second end surfaces 200 b of the conductive through-vias 200 inorder to absorb the laser, without the necessity of forming theconductive bumps 301. Consequently, the fabrication cost is increasedand the conductive bump must be made of a material having resistance tohigh process temperature and strong process solution.

FIGS. 4A, 4A′ and 4A″ are cross-sectional views illustrating a packagingsubstrates 4, 4′ and 4″ having an embedded through-via interposer 30according to a third embodiment of the present invention. The thirdembodiment differs from the second embodiment in that the circuit layerof the third embodiment is formed on the dielectric layer.

Referring to FIGS. 4A, 4A′ and 4A″, a circuit layer 231′ is formed onthe dielectric layer 230 of the built-up structure 23.

The present invention further provides a packaging substrate 3, 3′, 3″,4A, 4A′, 4A″having an embedded through-via interposer 30. The packagingsubstrate comprises an encapsulant layer 22 having a first surface 22 a,22 a′, 22 a″ and an opposite second surface 22 b, a through-viainterposer 30 embedded in the encapsulant layer 22, a redistributionlayer 21 embedded in the encapsulant layer 22 and formed on thethrough-via interposer 30, a built-up structure 23 formed on the secondsurface 22 b of the encapsulant layer 22, and an insulating protectivelayer 24 formed on the built-up structure 23.

The through-via interposer 30 has opposite first side 30 a and secondside 30 b, and a plurality of conductive through-vias 300 incommunication with the first side 30 a and the second side 30 b. Each ofthe conductive through-vias 300 has a first end surface 300 a on thefirst side 30 a of the through-via interposer 30 and a second endsurface 300 b on the second side 30 b of the through-via interposer 30,and an insulating layer 201 is formed on the sidewall of the conductivethrough-via 300. The second side 30 b of the through-via interposer 30is exposed from the second surface 22 b of the encapsulant layer 22. Thesecond end surfaces 300 b of the conductive through-vias 300 protrudeabove the second side 30 b of the through-via interposer 30 and thesecond surface 22 b of the encapsulant layer 22 so as to serve asconductive bumps 301.

The redistribution layer 21 is formed on the first side 30 a of thethrough-via interposer 30 and the first end surfaces 300 a of theconductive through-vias 300 and electrically connected with the firstend surfaces 300 a of the conductive through-vias 300. The outermostlayer of the redistribution layer 21 has a plurality of electrode pads210.

The encapsulant layer 22 covers the electrode pads 210, as shown in FIG.3E. Alternatively, referring to FIGS. 3E′ and 3E′, the electrode pads210 are exposed from the first surface 22 a′, 22 a″ of the encapsulantlayer 22.

The built-up structure 23 is disposed on the second side 30 b of thethrough-via interposer 30 and the second end surfaces 300 b of theconductive through-vias 300. The built-up structure 23 has at least adielectric layer 230, a circuit layer 231 embedded in the dielectriclayer 230 (as shown in FIGS. 3E, 3E′ and 3E″), and a plurality ofconductive vias 232 formed in the dielectric layer 230 for electricallyconnecting with the circuit layer 231. Portions of the conductive vias232′ electrically connect with the conductive bumps 301. The circuitlayer 231′ can alternatively be formed on the dielectric layer 230, asshown in FIGS. 4A, 4A′ and 4A″.

The insulating protective layer 24 has a plurality of openings 240 suchthat portions of the circuit layer 231 are exposed from the openings 240to serve as conductive pads 233.

According to the present invention, a through-via interposer is embeddedin an encapsulant layer to overcome the conventional drawback ofmismatch between packaging substrates and semiconductor chips havinghigh-density circuits without changing original supply chains andinfrastructures of IC industries, thereby meeting the demands forminiaturization and low-cost.

The above-described descriptions of the detailed embodiments are only toillustrate the preferred implementation according to the presentinvention, and it is not to limit the scope of the present invention.Accordingly, all modifications and variations completed by those withordinary skill in the art should fall within the scope of presentinvention defined by the appended claims.

What is claimed is:
 1. A packaging substrate having an embeddedthrough-via interposer, comprising: an encapsulant layer having oppositefirst and second surfaces; a through-via interposer embedded in theencapsulant layer and having opposite first and second sides and aplurality of conductive through-vias in communication with the first andsecond sides, wherein each of the conductive through-vias has a firstend surface on the first side of the through-via interposer and a secondend surface on the second side of the through-via interposer, and thesecond side of the through-via interposer is flush with the second endsurfaces of the conductive through-vias and the second surface of theencapsulant layer; a redistribution layer embedded in the encapsulantlayer and formed on the first side of the through-via interposer and thefirst end surfaces of the conductive through-vias so as to electricallyconnect with the first end surfaces of the conductive through-vias,wherein the outermost layer of the redistribution layer has electrodepads; and a built-up structure formed on the second surface of theencapsulant layer, the second side of the through-via interposer and thesecond end surfaces of the conductive through-vias, and having at leasta dielectric layer, a circuit layer embedded in the dielectric layer anda plurality of conductive vias formed in the dielectric layer forelectrically connecting with the circuit layer, wherein portions of theconductive vias electrically connect with the second end surfaces of theconductive through-vias, respectively.
 2. The packaging substrate ofclaim 1, wherein each of the conductive through-vias has an insulatinglayer formed on a sidewall of the conductive through-via.
 3. Thepackaging substrate of claim 1, further comprising an insulatingprotective layer formed on the built-up structure and having a pluralityof openings formed therein such that portions of the circuit layer ofthe built-up structure are exposed from the openings to serve asconductive pads.
 4. The packaging substrate of claim 1, wherein theencapsulant layer covers the electrode pads.
 5. The packaging substrateof claim 1, wherein the electrode pads are exposed from the firstsurface of the encapsulant layer.
 6. A packaging substrate having anembedded through-via interposer, comprising: an encapsulant layer havingopposite first and second surfaces; a through-via interposer embedded inthe encapsulant layer and having opposite first and second sides and aplurality of conductive through-vias in communication with the first andsecond sides, wherein each of the conductive through-vias has a firstend surface on the first side of the through-via interposer and a secondend surface on the second side of the through-via interposer, the secondside of the through-via interposer is exposed from the second surface ofthe encapsulant layer, and the second end surfaces of the conductivethrough-vias protrude above the second side of the through-viainterposer and the second surface of the encapsulant layer to serve asconductive bumps; a redistribution layer embedded in the encapsulantlayer and formed on the first side of the through-via interposer and thefirst end surfaces of the conductive through-vias so as to electricallyconnect with the first end surfaces of the conductive through-vias,wherein the outermost layer of the redistribution layer has electrodepads; and a built-up structure formed on the second surface of theencapsulant layer, the second side of the through-via interposer and theconductive bumps, and having at least a dielectric layer, a circuitlayer formed on the dielectric layer and a plurality of conductive viasformed in the dielectric layer for electrically connecting with thecircuit layer, wherein portions of the conductive vias electricallyconnect with the conductive bumps, respectively.
 7. The packagingsubstrate of claim 6, wherein each of the conductive through-vias has aninsulating layer formed on a sidewall of the conductive through-via. 8.The packaging substrate of claim 6, further comprising an insulatingprotective layer formed on the built-up structure and having a pluralityof openings formed therein such that portions of the circuit layer ofthe built-up structure are exposed from the openings to serve asconductive pads.
 9. The packaging substrate of claim 6, wherein thecircuit layer is embedded in the dielectric layer.
 10. The packagingsubstrate of claim 6, wherein the encapsulant layer covers the electrodepads.
 11. The packaging substrate of claim 6, wherein the electrode padsare exposed from the first surface of the encapsulant layer.
 12. Amethod of fabricating a packaging substrate having an embeddedthrough-via interposer, comprising: providing a through-via interposerhaving opposite first and second sides and a plurality of conductivethrough-vias in communication with the first and second sides, whereineach of the conductive through-vias has a first end surface on the firstside of the through-via interposer and a second end surface on thesecond side of the through-via interposer, and the second end surfacesof the conductive through-vias are flush with the second side of thethrough-via interposer; forming a redistribution layer on the first sideof the through-via interposer and the first end surfaces of theconductive through-vias such that the redistribution layer electricallyconnects with the first end surfaces of the conductive through-vias,wherein the outermost layer of the redistribution layer has electrodepads; forming an encapsulant layer to encapsulate and embed thethrough-via interposer, wherein the encapsulant layer has opposite firstand second surfaces, the second side of the through-via interposer andthe second end surfaces of the conductive through-vias are flush withthe second surface of the encapsulant layer, and the encapsulant layercovers the redistribution layer and the electrode pads; and forming abuilt-up structure on the second surface of the encapsulant layer, thesecond side of the through-via interposer and the second end surfaces ofthe conductive through-vias, wherein the built-up structure has at leasta dielectric layer, a circuit layer embedded in the dielectric layer,and a plurality of conductive vias formed in the dielectric layer forelectrically connecting with the circuit layer, wherein portions of theconductive vias electrically connect with the second end surfaces of theconductive through-vias, respectively.
 13. The method of claim 12,wherein each of the conductive through-vias has an insulating layerformed on a sidewall of the conductive through-via.
 14. The method ofclaim 12, wherein the circuit layer is formed by: forming the dielectriclayer; forming a plurality of intaglios in the dielectric layer; andforming the circuit layer in the intaglios of the dielectric layer. 15.The method of claim 12, further comprising forming an insulatingprotective layer on the built-up structure, and forming a plurality ofopenings in the insulating protective layer such that portions of thecircuit layer of the built-up structure are exposed from the openings toserve as conductive pads.
 16. The method of claim 12, further comprisingdecreasing the thickness of the encapsulant layer from the first surfacethereof so as to expose the electrode pads from the first surface of theencapsulant layer.
 17. A method of fabricating a packaging substratehaving an embedded through-via interposer, comprising the steps of:providing a through-via interposer having opposite first and secondsides and a plurality of conductive through-vias in communication withthe first and second sides, wherein each of the conductive through-viashas a first end surface on the first side of the through-via interposerand a second end surface on the second side of the through-viainterposer, and the second end surfaces of the conductive through-viasprotrude above the second side of the through-via interposer to serve asconductive bumps; forming a redistribution layer on the first side ofthe through-via interposer and the first end surfaces of the conductivethrough-vias such that the redistribution layer electrically connectwith the first end surfaces of the conductive through-vias, wherein theoutermost layer of the redistribution layer has electrode pads; formingan encapsulant layer to encapsulate and embed the through-viainterposer, wherein the encapsulant layer has opposite first and secondsurfaces, the second side of the through-via interposer is exposed fromthe second surface of the encapsulant layer, the conductive bumpsprotrude above the second surface of the encapsulant layer, and theencapsulant layer covers the redistribution layer and the electrodepads; and forming a built-up structure on the second surface of theencapsulant layer, the second side of the through-via interposer and theconductive bumps, wherein the built-up structure has at least adielectric layer, a circuit layer formed on the dielectric layer, and aplurality of conductive vias formed in the dielectric layer forelectrically connecting with the circuit layer, wherein portions of theconductive vias electrically connect with the conductive bumps,respectively.
 18. The method of claim 17, wherein each of the conductivethrough-vias has an insulating layer formed on a sidewall thereof. 19.The method of claim 17, further comprising forming an insulatingprotective layer on the built-up structure, and forming a plurality ofopenings in the insulating protective layer such that portions of thecircuit layer of the built-up structure are exposed from the openings toserve as conductive pads.
 20. The method of claim 17, wherein thecircuit layer is embedded in the dielectric layer.
 21. The method ofclaim 17, further comprising decreasing the thickness of the encapsulantlayer from the first surface thereof so as to expose the electrode padsfrom the first surface of the encapsulant layer.